Imaging description

Disc degeneration is accompanied by loss of hydration in the nucleus pulposus and declining structural integrity of the annulus fibrosus. The nucleus pulposus loses its high signal on T2-weighted images and there is a loss of disc height. Alterations in the adjacent vertebral endplates and vertebral marrow are commonly identified adjacent to the degenerated disc. These changes have been classified based on the pathologic changes in the vertebral endplate.

Modic type 1 marrow change signifies vascularized marrow, appearing hypointense on T1-weighted and hyperintense on T2-weighted sequences (Fig. 96.1). Type 2 changes occur with more chronic disc degeneration, with fatty changes in the adjacent marrow (Fig. 96.2). This type of degenerative change demonstrates high signal on T1-weighted and slightly high signal on T2-weighted images. Type 3 changes represent sclerosis and marrow fibrosis, resulting in dark signal on T1- and T2-weighted sequences [1]. The vertebral endplates in type 1 and type 2 change may enhance with contrast. There is relatively little evidence that the exact type of marrow changes harbor any clinical significance. However, it is imperative that radiologists be aware of the spectrum of signal abnormalities that can occur in the marrow and not confuse these with more sinister pathologies.